Maximal thymectomy for myasthenia gravis

The role of thymectomy in myasthenia gravis: A programmatic approach to thymectomy and perioperative management of myasthenia gravis

BACKGROUND

Myasthenia gravis is a rare autoimmune disease caused by antibodies that probably originate from the thymus glands. This study examined the epidemiology of patients with MG, who underwent thymectomy over the last three decades.

METHODS

The objectives of this observational study were to investigate the clinicopathological features, treatment modalities, and prognostic factors for patients with thymic masses, over three decades at the Royal Hospital, Muscat, Oman.

RESULTS

There were 100 patients who underwent thymectomy with a mean (SD) age of 32.0 (8.6) years, of which 20% were men and 80% were women. Their follow up period, cardiac and neurology clinics, ranged from 1.5 to 12.0 years with a mean (SD) of 6.0 (3.0) years. Small percentage of MG patients had diabetes and hypertension and 10% of patients have positive family history of MG. Symptoms at the onset of the disease were ophthalmoplegia in 75%, limb weakness in 39%, bulbar symptoms in 57% and respiratory symptoms in 39% of patients. The Osserman grading was Grade I - 5%, Grade IIA - 39%, Grade IIB - 34%, and Grade III - 22%. Post thymectomy, 21% of patients had complete clinical remission, 76% of patients had significant clinical improvement and 3% had no apparent improvement in their clinical status. Histologically, hyperplasia was found in 57% and involuted thymus in 18% of patients.

CONCLUSION

Thymectomy can reduce patient's need for medication and reduce the severity of MG regardless of age, sex, severity, or length of sickness, or thymic masses. The early-onset, sever M.G, female, thymic hyperplasia benefit the most. Patients classified as Osserman Class IIA and IIB benefit most from this procedure.

Predictors of Outcome for Myasthenia Gravis after Thymectomy

The aim of this study was to assess the clinical outcome of patients with myasthenia gravis treated with maximal thymectomy and to identify prognostic variables that predict the outcome. Over 15 years, from 1986 to 2001, we collected data on 100 patients with myasthenia gravis who underwent maximal thymectomy and retrospectively reviewed their outcome. Women comprised 63% and the median age was 25 years (range, 4 to 61). The median duration of the disease was 26 months (range, 1 to 240). According to the Osserman classification, there were seven patients in class I, 31 in class II, 47 in class III, and 15 in class IV. In non thymomatous patients (93 patients), complete remission rate progressively increased from 37.4% to 58.2% and 75% at 3, 10 and 15 years of follow-up respectively. These findings suggest that the complete remission rate is prone to increase with time after maximal thymectomy. The total benefit rate achieved was estimated to be 86% while 14% did not improve at a mean follow-up period of 7.6 years (range, 8 to 180 months). Univariate analysis ( p < 0.05) showed that age, thymic histology and ectopic thymic tissue are significant prognostic factors for outcome.

Extended transcervical thymectomy: the ultimate minimally invasive approach

The ideal operative technique for thymectomy in myasthenia gravis remains controversial. Most surgeons perform thymectomy through median sternotomy; more recently, thoracoscopic and robotic approaches have been described. "Extended transcervical thymectomy" is an out-patient procedure that appears less morbid and costly than other approaches. It allows a complete extracapsular thymic resection. Kaplan-Meier complete stable remission rates after transcervical thymectomy are 33% and 35% at 3 and 6 years (higher including patients remaining on single-drug immunosuppression). The major surgical complication rate is 0.7%. We believe that this less morbid and less costly operation is a very reasonable choice in the surgical treatment of myasthenia gravis.

Transsternal maximal thymectomy is effective for extirpation of cervical ectopic thymic tissue in the treatment of myasthenia gravis

PURPOSE

Extensive extirpation of cervico-mediastinal adipose tissue increases the chance of removing ectopic thymic tissues, thus potentially improving the prognosis of myasthenia gravis after thymectomy. We sought to increase efficacy and safety of transsternal maximal thymectomy (TSMT).

MATERIALS AND METHODS

Twenty four patients who underwent TSMT from July 2006 to June 2007 were retrospectively reviewed and compared with 73 patients who underwent transsternal extended thymectomy (TSET) from January 2004 to May 2006. Ectopic thymic tissue in additionally excised cervicomediastinal fat tissue was examined histologically.

RESULTS

In TSMT group, operation time, amount of cumulative drainage and duration of drainage were significantly higher than TSET group. However, the difference in hemoglobin count, amount of transfusion, duration of intensive care, postoperative hospital stay, and complication rates were not statistically different. There was no operative mortality in either group. Ectopic thymic tissue was found in 50% of patients. All patients had ectopic thymic tissues in the cervical area. Two patients had additional ectopic tissue in the aortopulmonary window, and 1 patient had ectopic tissue at posterior of the left bracheocephalic vein and lateral of the right phrenic nerve.

CONCLUSION

TSMT is more effective in the extirpation of ectopic thymic tissues than TSET without significant impairment of safety, especially in the cervical area.

Extended transcervical thymectomy in the treatment of myasthenia gravis

The ideal operative technique for thymectomy in myasthenia gravis remains controversial. Most surgeons perform thymectomy via median sternotomy, some supplementing this with an even more extensive mediastinal and cervical dissection designed to remove all areas of possible ectopic thymic tissue. We and others have advocated a transcervical approach that is less morbid and costly than sternotomy approaches. The transcervical approach allows a complete extracapsular thymic resection, but it does not address all areas of potential ectopic thymic tissue. We have published our experience with 151 extended transcervical thymectomies (TCT). At mean follow-up of 53 months (complete follow-up in 97%), Kaplan-Meier estimates of complete stable remission were 33% and 35% at 3 and 6 years. If one includes patients who became asymptomatic but remained on low dose, single-drug immunosuppression as complete remissions (CRs), then the CR rates were 43% and 45% at 3 and 6 years. Longer term (mean 83 months) follow-up of the earliest 84 patients in the series showed preserved CR rates. On multivariate analysis, only preoperative Osserman Class (group mean 2.3) was significantly associated with improved CR rate. These results were obtained with a major operative complication rate of 0.7% and minor complication rate of 6.6%, and nearly every operation was performed without the need for overnight hospital admission. We believe that these response rates following TCT are sufficiently similar to those following transsternal techniques of thymectomy to allow us to recommend this less morbid and less costly operation as an eminently reasonable choice in the surgical treatment of myasthenia gravis.

Myasthenia gravis: presentation and outcome in 104 patients managed in a single institution

BACKGROUND AND OBJECTIVES

Few studies have attempted to delineate the clinical profile of myasthenia gravis (MG) among people of Arab ancestry. Therefore, we sought to clarify the clinical profile, the outcome of treatment and the role of thymectomy in non-thymomatous MG in Saudi Arabia.

PATIENTS AND METHODS

We retrospectively studied 104 patients followed over a mean period of 7.2 years (range, 1 to 22 years) at the King Khaled University Hospital, Riyadh, Saudi Arabia. Disease outcomes were compared among thymectomized and non-thymectomized patients according to the post-intervention status criteria of the Myasthenia Gravis Foundation of America (MGFA).

RESULTS

Age of onset was 22.5+/-9.3 years (meanA+/-SD) in females and 28.2+/-15.9 years in males, with peaks in the second and third decades among females and the third and fourth decades among males. At diagnosis, a majority of patients had moderate generalized weakness, equivalent to MGFA class III severity. After medical treatment with or without thymectomy, 9.6% of all patients had achieved complete stable remission, 3.8% had pharmacological remission, 27.9% had minimal manifestations, 23.1% were improved, 20.2% were unchanged and 15.4% were worse. Only thymectomized patients without a thymoma achieved remission, a significant benefit over those who had no thymectomy (P=.02).

CONCLUSION

MG presents at a younger age among Saudi Arabs compared to other racial groups. Thymectomy conferred significant benefits towards achievement of remission.

Transsternal Thymectomy for Myasthenia Gravis: Surgical Outcome

BACKGROUND

Transsternal thymectomy is well established in the treatment of myasthenia gravis. Surgical strategy and patient selection, however, remain controversial. This paper reports the experience of a supraregional center looking into the influence of different preoperative risk factors on surgical outcome.

METHODS

Between 1987 and 1998, 85 consecutive patients (65 female; mean age, 30.5 years) were enrolled. The mean preoperative Myasthenia Gravis Foundation of America stage was 2.3. The preoperative, early, and late follow-up data were analyzed retrospectively.

RESULTS

Mean follow-up was 4.5 years (range, 1 to 14; 376 follow-up years). Mean duration of disease before surgery was 31 months. There were no operative or late deaths. Eight patients had major complications. Seventy-two patients were free from any early or late morbidity. Immunosupression therapy patients were more prone to have complications. At their last visit, 15 patients (17%) were in complete remission; 67 reported clinical improvement. Sixty-three were asymptomatic or in stage I on no or minimal treatment. Remission and clinical improvement were not predicted by patient's age, sex, duration of disease prior to surgery, thymic pathology, or antiacetylcholine receptor antibodies titer. Greater severity of symptoms before surgery was associated with greater subsequent improvement. Remission at 1 year predicted remission at the end of follow-up.

CONCLUSIONS

Transsternal thymectomy for myasthenia gravis is safe and effective. It benefits most patients, especially those with severe symptoms. The long interval from diagnosis to surgery demonstrates it is never too late for thymectomy.

Video-Assisted Thoracoscopic Thymectomy for the Treatment of My asthenia Gravis

OBJECTIVE

Traditionally, thymectomy for myasthenia gravis has been performed using either a transcervical approach or a median sternotomy. However, excision of the thymic tissue by video-assisted thoracoscopic surgery is less aggressive and recovery is faster. The aim of this study was to evaluate the usefulness and outcomes of video-assisted thoracoscopic thymectomy.

PATIENTS AND METHODS

Over the past 10 years, we have performed 25 video-assisted thoracoscopic thymectomies on patients with myasthenia gravis at our unit. This study included 16 women and 9 men, with a mean age of 48.1 years (range, 14-74 years). Right-side (22 cases) or left-side (3 cases) thoracoscopic surgery was performed, with a mean intervention time of 110 minutes (range, 60-193 minutes).

RESULTS

No patient required assisted ventilation for more than 4 hours and the maximum stay in intensive care was less than 24 hours. Complications from surgery included 3 cases of contralateral pneumothorax, 1 pleural effusion, and 2 intraoperative hemorrhages from the thymic vein, all of which were resolved by video-assisted thoracoscopy. Likewise, 3 cases required conversion (due to hemorrhaging in 2 patients and technical difficulties in 1) and 2 required a second thoracoscopic intervention. No deaths occurred and clinical outcome was excellent in 11 cases (medical treatment no longer required), good in 10 (reduced medical treatment), and poor in 4 (no changes).

CONCLUSIONS

Video-assisted thoracoscopic thymectomy is effective in the treatment of myasthenia gravis and improves patient recovery. In addition, the excellent surgical view allows the thymectomy to be performed with absolute safety.

The immunologic role of thymectomy in the treatment of myasthenia gravis: implication of thymus-associated B-lymphocyte subset in reduction of the anti-acetylcholine receptor antibody titer

BACKGROUND AND PURPOSE

Thymectomy is generally accepted as the major option of treatment for myasthenia gravis. To elucidate the biological role of thymectomy in the treatment of myasthenia gravis, the immunologic characteristics of the thymus was studied in association with the postoperative kinetics of the anti-acetylcholine receptor antibody titer.

MATERIALS AND METHODS

Thirty-four patients with nonthymomatous myasthenia gravis who had positive anti-acetylcholine receptor antibody titer and undergoing extended thymectomy were subjected to the study. Reduction of anti-acetylcholine receptor antibody titer was evaluated in terms of the proportion of anti-acetylcholine receptor antibody titer at 1 year after thymectomy to that before the operation. The numbers of B lymphocytes (CD19(+) cells) and the germinal center B lymphocytes (CD19(+)CD38(high) cells) present in 1 g of the thymic tissue were calculated by flow cytometry.

RESULTS

The proportion of anti-acetylcholine receptor antibody titer at 1 year after thymectomy ranged from 27.5% to 150%. The numbers of B lymphocytes and the germinal center B lymphocytes in 1 g of the thymic tissue ranged from 0.19 x 10(6)/g to 162.8 x 10(6)/g and from 0.09 x 10(6)/g to 33.4 x 10(6)/g, respectively. The proportion of anti-acetylcholine receptor antibody titer at 1 year after thymectomy had a significant inverted correlation with the number of B lymphocytes (P =.002) as well as that of the germinal center B lymphocytes (P =.007).

CONCLUSION

Effectiveness of thymectomy was dependent on predominance of B lymphocytes and the germinal center B lymphocytes in the thymus, suggesting that one of the biological roles of thymectomy in the treatment of myasthenia gravis is removing the thymus-associated germinal centers.

Thymectomy for myasthenia gravis: analysis of controversies--patient management

BACKGROUND

Debate continues regarding the effectiveness of thymectomy in the treatment of nonthymomatous autoimmune myasthenia gravis primarily because there have been no controlled prospective studies. The debate is compounded by the lack of recognition that all thymectomies are not equal in extent or effectiveness and by the fact that all the studies are retrospective without common definitions of myasthenia gravis manifestations or response to therapy. In addition, the analysis of data is often inappropriate.

REVIEW SUMMARY

Evidence is presented demonstrating that the extent of the various thymic resectional techniques is very variable and often incomplete and that the more complete the thymic resection the better the results. The indications for thymectomy, the selection of the technique of the resection, the reoperations issue, the perioperative management of the myasthenia gravis patient, morbidity and mortality, and appropriate methods of outcome research are also reviewed.

CONCLUSION

In view of the impressive results associated with a complete thymic resection in the treatment of myasthenia gravis, patients should not be denied this operation because of lack of prospective proof to-date, and when a thymectomy is performed a total resection is indicated.

Transcervical thymectomy for myasthenia gravis achieves results comparable to thymectomy by sternotomy

BACKGROUND

It remains controversial whether transcervical thymectomy offers results equivalent to thymectomy by way of a median sternotomy in the treatment of myasthenia gravis. Furthermore, preoperative prognostic factors have not been clearly defined.

METHODS

This study is a retrospective chart review and interview of 78 patients completing transcervical thymectomy for myasthenia gravis between 1992 and 1999.

RESULTS

There were 24 men and 54 women. Mean age was 40 years (range, 13 to 78 years). Twelve patients were in Osserman class 1, 25 in class 2, 30 in class 3, and 11 in class 4 (mean, 2.5). There was no perioperative mortality and 6 (7.7%) morbidities. Mean length of stay was 1.5 days and mean follow-up, 54.6 months. The crude cumulative complete remission (asymptomatic off medications for 6 months) rate was 39.7% (n = 31). Only 8 patients (10.3%) failed to improve after transcervical thymectomy. Kaplan-Meier estimates of complete remission were 31% and 43% at 2 and 5 years, respectively. Eight patients with thymoma had a 5-year estimated complete remission rate of 75% in contrast to 43% in 38 patients with thymic hyperplasia and 36% in 32 patients with neither thymoma nor hyperplasia (p = 0.01). Twelve patients with ocular myasthenia had a 5-year estimated complete remission rate of 57%, whereas patients with mild-to-moderate (n = 55) or severe (n = 11) generalized symptoms had 5-year complete remission rates of 43% and 30%, respectively (p = 0.21).

CONCLUSIONS

Overall, extended transcervical thymectomy offers results that are comparable to those published for the transsternal procedure. Patients with milder disease (including isolated ocular disease) and taking no preoperative immunosuppressive agents appear to experience higher remission rates. In contrast to previous studies, we also find that small thymomas predict better responses to thymectomy.

Thymectomy for myasthenia gravis

The pathophysiological role of the thymus in myasthenia gravis, and the mechanism of therapeutic effect of thymectomy, are incompletely understood. Nevertheless, thymectomy is a valuable treatment modality in selected patients with generalised myasthenia gravis. There are several types of thymectomy operation, but no one operative approach is clearly superior to the others. Total removal of the thymus gland is essential. Additional excision of associated mediastinal and cervical tissue, that may harbor ectopic thymic rests, is a controversial surgical issue. Surgeons that advocate thymectomy through small, cosmetically favourable, incisions usually believe that simple removal of the thymus gland is an adequate operation. Surgeons that emphasise the importance of removing extrathymic tissue, in addition to the thymus gland, usually favour greater operative exposure through a median sternotomy. To minimise operative morbidity, surgery for myasthenia gravis requires a multidisciplinary (neurology, surgery, anaesthesia) approach to peri-operative care.